1. Field of the Invention
The invention relates to a tape carrier for TAB for mounting an integrated circuit component, an integrated circuit device packaged with an integrated circuit component mounted therein, a method of making the same, and an electronic device.
2. Description of Related Art
Recent liquid crystal display devices use an integrated circuit device having a driver integrated circuit component mounted thereon for the purpose of connecting the LCD cell to its driver circuit. Such an integrated circuit device generally adopts either the TAB method using a so-called TAB package (also known as a TCP (Tape Carrier Package)), or the COG (Chip On Glass) method in which the driver integrated circuit component is directly connected to the glass substrate. Particularly a TAB package has many advantages, being more compact and thinner than other packages, and appropriate for high-density mounting, allowing electrical testing on a tape carrier, and also permitting mounting in a flexed position; for these reasons it has been widely adopted not only for liquid crystal display devices, but also for other electronic devices.
A conventional TAB package, as shown in FIG. 14, has a tape carrier 131 formed of polyimide or the like, in which is formed a device hole 133 of dimensions larger than the dimensions of an integrated circuit component 132 to be mounted thereon. Inner leads 134 projecting within the device hole 133 are connected by way of bumps 135 to electrodes of the integrated circuit component 132. Moreover, to prevent short-circuits between inner leads 134 or contact of the inner leads 134 with the integrated circuit component 132, and to improve reliability, a protective resin 136 covers the inner leads 134 and the surface of the integrated circuit component 132. The electrodes and bumps 135 are normally disposed along the periphery of the integrated circuit component 132, in order that the lengths of the inner leads 134 are as short as possible in the one-sided holding state (that is, in the state where one side only of the inner leads 134 is supported by the tape carrier 131). Additionally, as disclosed in Japanese Patent Application Laid-Open No. 63-95639, a construction is also known in which in order to mount an integrated circuit component of large scale and having a large number of electrodes, a lead support portion extending into the device hole is provided on the tape carrier, and some of the leads extend thereover.
However, a conventional TAB package as described above has a gap between the peripheral edges forming the device hole 133 and the peripheral edges of the integrated circuit component 132, and the protective resin 136 is provided in order not to expose the inner leads 134 in this gap. As a result, the outer dimensions of the package are considerably larger than the outer dimensions of the integrated circuit component 132 and the mounting area is increased. Additionally, with the miniaturization of the integrated circuit component 132, and a closer pitch for the electrodes and inner leads 134, connecting leads 134a supported on the tape carrier 131 are required to be finer, and a large area is required to bring out the connecting leads 134a since the wiring distance is increased. For this reason, the area of tape carrier used for mounting a single integrated circuit component 132 is increased, the overall package dimensions are further increased, and the mounting area is increased, resulting in a problem of going against the requirement to make the electronic apparatus more compact.
In particular, in the case of a liquid crystal display, as shown in FIG. 15, a plurality of TAB packages 138 (only one of which is shown in the figure), each having a driver integrated circuit component 137 mounted thereon, is connected along the periphery of an LCD cell 139, and further on the outer side thereof is connected a printed circuit board 140 forming a drive circuit. With respect to the overall dimensions of the liquid crystal display device, to increase the liquid crystal display area, it is necessary to reduce the width W of the so-called frame portion. For this purpose, it is necessary, while reducing each of the width w1 of the outer periphery 141 of the LCD cell 139 connected to the TAB package 138 and the width w2 of the printed circuit board 140, to make the TAB package 138 smaller, and thus to reduce its width w3. For this purpose, it is possible first to consider making the driver integrated circuit component 137 smaller, and reducing the corresponding width as much as possible, but in a TAB package of the above-described conventional construction, it is difficult to go smaller than the current size, and there is a problem that the width W of the frame portion cannot be adequately reduced. On the other hand, with the COG method, the connection leads are also formed at the periphery of the LCD cell 139 in addition to a driver integrated circuit component being directly mounted, and it is therefore more difficult to reduce the width W of the frame portion than in the TAB method.
Additionally, with the increasing compactness of electronic apparatus another problem arises. For example, with the move to fine high output pin counts, one of integrated circuit components, employed in a liquid crystal display device or the like, has an elongated shape and electrodes disposed in two rows along its long dimension with wires lead-out in two directions. Such an integrated circuit component and tape carrier are shown in FIG. 16. In this figure, an integrated circuit component 142, and inner leads 144 formed on a tape carrier 143 are connected by thermal bonding by a bonding tool (thermal bonding tool) not shown in the drawing. Here the tape carrier 143 has a large coefficient of thermal expansion with respect to the integrated circuit component 142. For this reason, when the two are subjected to thermal bonding, the tape carrier 143 is thermally bonded in the extended state to the integrated circuit component 142. However, after the thermal bonding, since the tape carrier 143 shrinks with the fall in temperature, the tape carrier 143 pulls the inner leads 144, and the tape carrier 143 is deformed in an arc shape in the vicinity of the integrated circuit component 142. Moreover, as the tape carrier 143 pulls the inner leads 144, there is a possibility of breakage of the inner leads 144.